replacement oxygen sensor SL450 1980

[Philfi]

Hi I own a R107 SL450 from 1980
I want to replace the Lambda sensor but could not find exact match of O2 sensor.
Original part nbr is A002 542 1218 or Bosch 0258001040.

I could not find identical match but purchased new sensor that was supposed to be compatible (Bosch 0258001051)

I now have a question re the wiring. Original wiring has pos and neg in one wire and ends in connector with +/-.

The new sensor only has one single wire. Assume ground is on the sensor itself connecting to the exhaust pipe.

How do I now convert the new in to the old plug. How can I connect the new sensor using the same original connector.

Thanks for support

 

[LostKiwi]

It sounds like it's not a compatible sensor I'm afraid.
If it works at all the wire from the sensor will connect to the + and use an earth reference.

 

[Philfi]

Thanks for your feed back.
I wonder if I could convert the original connector to link standard +, and then apply grounding to the sensor and supply second ground wire to the original connector.
The original sensor is not for sale, I scanned the web but could not find it.
Quid?
cheers
P

 

[Philfi]

attached picture of both sensors old and new

 

[mioba]

I would take a trip your local dealer and get one from there

 

[LostKiwi]

Can you post a picture of the end of the connector?

 

[mattkh]

Clean the wires to the connector to show the colours before the photo

 

[mioba]

Did you ebay the part no., no spaces

https://www.ebay.co.uk/itm/Mercedes...793335&hash=item1eb9887759:g:u6wAAOxygPtS2CaR

They clearly provide a crimp, so you might just have to get handy with the soldering iron..

 

[Philfi]

below some more pics, the original is wired with coax type cable, hard wire in the middle surrounded by braided wire. The braided wire is linke to the ground of the sensor. The original connector couples both pos and ground from the sensor.
The new sensor only has one single wire coming out, ground via the sensor on the mass of the car.
So how do i connect the new sensor to the original connector. How can i connect normal single wire to coax double single cable?
thanks for all tips
I checked the web and local mercedes garage to buy original plug, but could not find it.

 

[LostKiwi]

Ok that makes more sense.
Cut the old connector off the cable leaving at least 2" of wire attached.
With a Stanley knife carefully cut the outer insulation away about 1" to reveal the braided sheath. Carefully unravel the braided sheath to expose the central wire and remove. Strip 1/2" of the insulation off the inner sheath. Cut the connector off the new sensor and strip 1/2" of insulation. Slide a piece of heat shrink tubing over the wire of the new sensor. Solder the two ends of the wire together, allow to cool then slide the heat shrink tubing over the join and gently heat to insulate and seal the join.
Don't worry about the braided shield as the sensor will earth through the exhaust system.

 

[Philfi]

Thanks for the instructions, Still not 100% sure. The original connector has both poles, ground and pos. If I understand your method, I will only connect + to the connector. Earth of the sensor will come via the exhaust so no longer via the connector?

 

[LostKiwi]

Thanks for the instructions, Still not 100% sure. The original connector has both poles, ground and pos. If I understand your method, I will only connect + to the connector. Earth of the sensor will come via the exhaust so no longer via the connector?

Correct.
The exhaust is bolted to the engine and the engine is connected to battery earth.

 

[Philfi]

thanks a lot, just connected the sensor and the engine runs smoother and not so rich as before.
measured the sensor once heated and it gives voltage between 0,1 and 0,9 as needed so works fine.
I let the engine rune for 10 minutes and it really funs fine.
After switching off I could not re-restart. With hot engine I can not get it running.
Anny idea what this could be?
cheers
P

 

[LostKiwi]

Disconnect the sensor. Does it run?

 

[Philfi]

will try tomorrow battery is empty, keep you posted cheers p

 

[mioba]

will try tomorrow battery is empty, keep you posted cheers p

Maybe answered your own question there

 

[mattkh]

I keep thinking about the braided wire.
Is it too late to connect a wire to the braid and connect the other end to the body of the oxygen sensor OR to a chassis point close by.

 

[LostKiwi]

There really is no need.
If you have a multimeter measure resistance between the braid and chassis and measure the resistance.

 

[Philfi]

after I installed the new oxygen sensor the engine run much better (less rich as before)
Only i can not start the engine anymore. It simply will not fire. Tested the fuel pump and this works, sprayed some engine starter in the air filter and than the motor kicked off. (so no ignition problem).
what could be the reason i do not get fuel to the engine.
could i have blown up the ECU with installation of new oxygen sensor?

 

[LostKiwi]

If you'd blown the ECU it probably wouldn't work at all.
Did you try restarting with the O2 sensor disconnected?